Amplitude detector circuits have been developed for measuring oscillating analog signal amplitudes. Often, where the impedance at which the amplitude is measured is known, a measurement of the signal amplitude can be used to measure the signal power. Thus, under such circumstances the amplitude detector circuit can also be a power meter. For example, in a mobile telephone, smart phone, bluetooth device, or any other wireless device, the power of a radio frequency (“rf”) signal transmitted from the wireless device to a base station can be monitored and controlled to maintain the output power close to the maximum allowable power. Similarly, the power of an rf signal received by a wireless device can be amplified, monitored, and controlled to provide reliable reception of the signal.
Many amplitude detector circuits rely on a rectifying diode to measure the amplitude of the analog signal. However, the gain of the rectifying diode often generally is temperature-dependent, so the accuracy of a amplitude measurement made with such a circuit may vary with temperature. Moreover, the accuracy of amplitude detector circuits that rely upon solid state devices, such as transistors, can depend on the temperature of the devices, variations in the performance parameters of individual devices, and variations in the performance between different instances of nominally-identical devices that include such detector circuits.